Neither Strahan, the former Giants football star who has been her co-host for four years, nor network brass gave Ripa advance notice of his departure, sources said. The personnel change was announced publicly soon after Ripa and the show’s executive producer, Michael Gelman, were told by brass.

“Kelly didn’t want to show up to work and mouth off and say something she would have regretted,” explained another insider. “She is upset and didn’t want to take it out on her own staff.”

Ripa will be out until at least next Tuesday.

“Dancing with the Stars” host and Fox sports reporter Erin Andrews subbed on Thursday. Andrews will also appear on Friday’s show, which was already scheduled to be taped Thursday.

“Pretty Little Liars” star Shay Mitchell is to co-host with Strahan on Monday.

“Some of [Kelly’s days off] may have been planned before the news broke,” a third network source said. “[The show] is dark on Friday, so there’s no show anyway, and I had heard that Kelly already planned to be off on Monday.”

Kelly Ripa and Michael Strahan on the set of “Live”David E. Steele/Disney ABC

“She didn’t show up for work and isn’t taking anyone’s calls,” a source said.

Ripa’s sudden sick-out left Strahan holding the bag with viewers.

“Kelly’s off today,” Strahan began at the top of Wednesday’s show. “I’ve been in the news lately,” the popular ex-NFL star acknowledged.

“I’m leaving this show to go over to ‘GMA’ full-time, which is going to happen in September,” he added.

He consoled the groaning studio audience.

“It’s the same channel!” he said. “I’m not going anywhere. I was reading some stuff that sounded like I died!”

He added, “I’ve worked with an incredible staff here, and I’m always here. I’m always available to guest co-host if I get a call because I consider myself to be a part of this family forever.”

The network’s fumbling of the job change left insiders scratching their heads.

“The plan was for there to be more time between telling Kelly and the announcement,” one source told Page Six. “But the story leaked, and the timeline got crunched.”

And while one insider derided Ripa’s sick-out as “classic diva behavior,” others thought she was justified in staging a brief, one-woman strike.

“You work on a show for 15 years and all of a sudden you’re not even told about this seismic change?” was how one put it.

Without Ripa at his side, Strahan had to address his first on-air farewell to the cameras.

“I really want to thank, of course, Kelly Ripa,” he said at the end of Wednesday’s show, to applause from the studio audience.

“Kelly welcomed me here, and I’ve learned so much from her, and she’s just been an amazing influence on me,” he said. “This has truly changed my life to be here with her . . . Kelly, I thank you. I love you.”

When asked to comment on Ripa’s absence, a “Live” spokesperson said only, “Kelly had the day off today.”